1. Field of the Invention
The present invention relates to an improvement of a driving force transfer system in a hybrid vehicle.
2. Description of the Background Art
As a power system in a hybrid vehicle there is known, for example, "a hybrid propulsion system for a vehicle, especially for a streetcar" which is disclosed in Japanese Patent Laid Open No. 218430/92.
As shown in FIG. 1 of the unexamined publication, the above known system is provided with an internal combustion engine 10 and a motor 20. A driving force generated by the internal combustion engine 10 is transmitted to a shaft 16 through a belt 25 and a clutch 14, then from the shaft 16 it is transmitted to a vehicle wheel 26 through gears 17, 18 and a shaft 19. On the other hand, a driving force generated by the motor 20 is transmitted to the shaft 16 through a free wheel 24 which is a one-way clutch to assist the internal combustion engine 10.
However, in the prior art referred to above, since the driving force of the motor 20 is transmitted to the shaft 16 through the free wheel 24 (one-way clutch), it is impossible to transmit the driving force of the internal combustion engine 10 to the motor 20 side. Thus, the motor 20 cannot be used as a generator and it is impossible to charge batteries with use of the motor 20.
Nor is it possible to rotate the vehicle wheel 26 in the opposite direction with the motor 20 to move the vehicle backward.